Head band for frameless stereotactic registration

Abstract

A skin-based band is fixed to a patient's skin in a repeatable position and includes reference markers which, attached to the skin band, can be visualized in tomographic image scanning. The reference markers appear as reference marker images in the image scan data from the image scan and correspond to coordinate positions in the image scan coordinate system. The reference markers also provide corresponding reference marker positions in the physical space of the patient's anatomy, which may correspond to a stereotactic coordinate system associated with a digitized navigator or frameless stereotactic reference system near the patient. The band can also be placed on the patient again at the time of surgical intervention, and the reference markers can be touched or referenced by the surgical navigator in the stereotactic coordinate system. A computer system assimilates the image scan data and calibration data and enables a mapping from the image scan coordinate system to the stereotactic coordinate system so that surgical instruments can be tracked by a surgical navigator so that their position can be referenced to the image scan data.

We claim: 
     
       1. A stereotactic localizer system for localizing positions in a patient's anatomy based on an image scan of said patient's anatomy comprising: a. a skin band adapted to be fixed to the patient's skin of said patient's anatomy;   b. reference markers connected to said skin band and detectable in image scan data produced by said image scan and having image positions in an image scan coordinate system and/or said image scan data, and having physical positions with respect to stereotactic coordinate system associated with an external apparatus near said patient's anatomy, such that said image scan coordinate system can be mapped into said stereotactic coordinate system by a transformation from said image positions to said physical positions; and,   c. further including dynamic reference structures attached to said skin band, said dynamic reference structures having a pattern which can be detected by a detection apparatus that is in a position with respect to said stereotactic coordinate system, such that changes in position of said patient's anatomy with respect to said stereotactic coordinate system can be detected by said detection apparatus and accordingly corrections in said mapping between said image scan coordinate system and said stereotactic coordinate system can be made.   
     
     
       2. The apparatus of claim 1 wherein said skin band comprises a head band that can be attached to the head of the patient. 
     
     
       3. The apparatus of claim 1 wherein said reference markers comprise radiopaque markers which can be detected in a CT scan image through said patient's anatomy. 
     
     
       4. The apparatus of claim 3 wherein said radiopaque markers comprise radiopaque rings having through holes such that ink dot markings can be made on said patient's skin through said through holes. 
     
     
       5. The apparatus of claim 1 and further comprising a graphic reference structure which can be detected as varying data in said image scan data such that individual slice images from said image scan data can be indexed with respect to said patient's anatomy such that corrections in said image scan data resulting from changes in the position of said patient's anatomy with respect to said image scan and/or said image scan coordinate system can be made. 
     
     
       6. The apparatus of claim 5 wherein said graphic reference structure includes diagonal elements which produce varying index data in said image scan data whereby a mapping can be made from the coordinate system of said graphic reference structure to said image scan coordinate system.